基于系统可靠度的空间网格结构优化分析

以空间网格结构的杆件截面为基本变量,提出了以结构的最小重量为目标函数,把结构系统的可靠度作为约束条件,采用改进的遗传算法的空间网格优化理论,从而避免了对结构系统可靠度进行复杂的敏度分析,降低了系统可靠度约束下的结构优化的难度。通过算例表明,优化结果令人满意,且收敛性较好,表明了该方法的可行性。     

某体育馆双层柱面网壳结构的优化设计

系统介绍了某体育馆双层柱面网壳结构的优化设计。通过APDL语言在ANSYS环境中利用满应力方法实现不同工况下杆件截面的离散变量优化,并分析截面优化的稳定性、收敛性与可靠性。利用遗传算法在MATLAB环境中实现网格类型、网格数、厚度、矢高的正整数变量优化。联合利用上述方法编制相关程序,实现了结构的多变量的综合优化,取得了较理想的优化效果。该种方法对空间网格结构优化设计具有通用性。     

空间网格结构基于离散变量的优化设计

空间网格结构离散变量的优化设计是空间网格结构的截面尺寸优化、形状优化、拓扑优化和布局优化的理论基础。本文在建立空间网格结构离散变量优化设计问题数学模型的基础上,分析了空间网格结构离散变量优化设计的特点和算法效率。文中采用相对差商法。对空间网格结构杆件截面尺寸的离散变量优化设计问题进行了研究和探讨。文章最后给出了两个算例,计算结果验证了本文理论的正确性和有效性。     

基于风洞试验成果的大跨度网壳结构优化

以某大跨度网壳结构为研究对象,对建筑结构进行了风洞试验.将风洞试验体型系数结果引入大跨度网壳结构并优化设计.应用复形法建立了网壳结构目标函数,初步拟定网壳结构的网格尺寸、网壳厚度、网壳矢高,以杆件的截面面积为设计变量,杆件的强度和最小截面尺寸为约束条件,并编制了相应的程序,对三圆弧网壳结构外形尺寸进行多种方案的优化设计,比较试验与规范风载体型系数优化结果,为类似网壳结构设计提供参考.     

建筑结构优化的模型选取

针对建筑结构优化中大型结构截面与构件形式丰富,约束复杂,荷载组合多等特点,从缩减变量、选取目标函数、整合约束条件等方面提出符合工程需要的建议,并可结合适当的优化准则编制成结构优化程序,在工程中有一定的适用性。     

高层建筑结构优化的若干建议

针对高层建筑结构优化中大型结构约束复杂,荷载组合多,截面与构件形式多样等特点,从优化变量、目标函数、约束条件等几个优化中最根本的问题出发,提出符合工程需要的建议,结合适当的优化准则编制成结构优化程序,对高层建筑结构优化设计有一定的借鉴作用。     

基于遗传算法的结构可靠度计算

遗传算法(GA)作为一种优化算法,用于结构可靠度分析,对目标函数和约束条件没有过于苛刻要求,利用MATLAB软件,引入遗传算法编制相应程序,验证已知功能函数的结构构件的可靠度。工程实例计算表明,结合遗传算法分析结构体系可靠度,不受搜索空间的限制性假设的约束,不要求目标函数具有连续性、可导等假设,其结果与其他算法结果具有一致性。     

基于离散变量的大跨度钢桁架网壳优化设计

以大型通用有限元软件ANSYS为运行环境,以杆件截面为设计变量,以工程造价为目标函数,采用基于离散变量的满应力法中的应力比法对大跨度空间网架结构进行截面优化设计。同时考虑网架结构的强度、刚度、稳定性、杆件截面尺寸等约束条件。采用FORTRAN语言编制网架优化程序与ANSYS接口。以某煤炭工业厂房的大跨度空间筒壳结构为工程实例,对其进行优化设计,取得了较明显的效果。     

ANSYS环境下的网壳结构优化设计

以大型通用有限元分析软件ANSYS作为运行环境,介绍了ANSYS中结构优化的方法及步骤、网架优化设计中设计变量、状态变量及目标函数的选取.将网壳结构的杆件截面面积作为设计变量,以网壳结构的总质量为目标函数,同时考虑网壳结构的强度、刚度、稳定性、杆件截面尺寸等约束条件,以塔里木油田分公司塔里木生活基地体育馆工程中的球类馆为工程实例,分别在恒载 活载和风荷载两种工况下,对六榀主拱桁架用到的14种钢管截面进行优化,取得了较明显的效果.     

基于序列线性规划的空间钢框架优化

基于序列线性规划和对偶仿射尺度法,以结构用钢量最低为优化目标,以截面尺寸为优化变量,推导了空间钢框架结构整体优化有限元模型。通过编程实现结构在包括杆件强度、稳定,节点位移,结构层间位移角的多种约束条件下的优化设计。以一个简单不规则钢框架算例验证了优化程序的可行性;通过收缩约束条件验证了程序主动控制不同应力、位移约束的效果。对一个主次梁体系结构进行优化设计,同时考虑规范对构件、结构的多项限值,验证了优化算法和程序能够满足工程实际的需要。     

Multiobjective optimization of modular structures: Weight versus geometric versatility in a Truss‐Z system

This paper proposes an approach for multicriterial optimization of modular structures with respect to their structural and geometrical properties. The approach is tested using the quickly deployable and reconfigurable modular ramp system Truss‐Z intended for pedestrian traffic. The focus is on modular structures composed of a moderate number of relatively complex modules, which feature an irregular, noncuboidal geometry. Such modules can be assembled into a variety of geometrically different configurations which do not adhere to any predefined spatial grid; their global geometry can be treated as free‐form and determined in situ during construction. The optimization variables represent local‐level geometrical and structural properties of a single module. The Pareto front is used to balance between two kinds of objectives. The geometrical objective quantifies the ability of the modules to generate geometrically versatile global structures that are well‐suited to comply with spatial constraints of real construction sites. The structural objective is formalized in analogy to the minimum weight problem with upper bound constraints imposed on the von Mises stress and the Euler buckling load ratio. A two‐level optimization scheme is employed with NSGA‐II at the top level and a simulated annealing with adaptive neighborhood at the lower level.     

改进的三角锥体系网格结构形状语法规则

网格结构拓扑优化是一个极具挑战性的领域,关于结构节点和单元的增加与删除问题一直难以解决.结构形状的表述(即形状语法)是结构生(合)成理论的关键,是建立结构优化初始模型的基石.为改善优化进程以使结构达到最佳状态,同时加快结构寻优效率,提出改进的三角锥体系网格结构形状语法规则,旨在优化用于生成三角锥空间网格结构的形状语法规...     

三角锥体系网格结构的形状语法规则的建立

结构生(合)成理论已被初步应用于数值化概念设计中,在平面类桁架结构的生成与实现已有初步成果.以三角锥体系空间网格结构为研究对象,构建用于生成三维空间网格结构的形状语法规则和用于结构优化控制的设计评估准则,将基于性能的计算生(合)成理论由二维受力的平面桁架和桁架梁的设计延拓至三维空间网格结构的数字化生成与实现,旨在构建用于生成三角锥三维空间结构的形状语法规则,为后期的结构优化控制的设计做准备.     

互承式空间网格结构找形方法研究

互承式空间网格结构是一种以杆件相互搭接为特征的杆系结构，具有连接构造简单、富于韵律美感的特点。由于互承式空间网格结构的形状受杆件搭接关系的影响，因此该类结构设计中的关键问题是找到同时满足杆件搭接关系和建筑造型要求的结构形状。为此，推导了杆件搭接系数，实现了对杆件搭接关系的量化描述，采用二分法实现了杆件搭接过程的数值模拟。基于结构实际搭建过程，提出一种互承式空间网格结构找形方法。该方法按照一定顺序依次提升平面互承网格的每个杆件节点，通过反复迭代使所有节点满足设定的杆件搭接系数，从而实现互承式空间网格结构的循环搭接找形。算例分析表明：所提方法的计算效率明显优于已有基于结构优化算法的找形方法，杆件搭接系数、旋转角度和网格疏密程度是影响互承式空间网格结构形状的主要参数，调整这些参数能够使结构整体形状趋近建筑造型要求。     

Comparative seismic design optimization of spatial steel dome structures through three recent metaheuristic algorithms

Steel dome structures, with their striking structural forms, take a place among the impressive and aesthetic load bearing systems featuring large internal spaces without internal columns. In this paper, the seismic design optimization of spatial steel dome structures is achieved through three recent metaheuristic algorithms that are water strider (WS), grey wolf (GW), and brain storm optimization (BSO). The structural elements of the domes are treated as design variables collected in member groups. The structural stress and stability limitations are enforced by ASD-AISC provisions. Also, the displacement restrictions are considered in design procedure. The metaheuristic algorithms are encoded in MATLAB interacting with SAP2000 for gathering structural reactions through open application programming interface (OAPI). The optimum spatial steel dome designs achieved by proposed WS, GW, and BSO algorithms are compared with respect to solution accuracy, convergence rates, and reliability, utilizing three real-size design examples for considering both the previously reported optimum design results obtained by classical metaheuristic algorithms and a gradient descent-based hyperband optimization (HBO) algorithm.     

Structural dynamic optimal design based on dynamic reliability

In this work, dimension and shape optimization of structures under stochastic process excitation is addressed in the context of element or system dynamic reliability constraints, where the structural gross mass is taken to be the objective function. Firstly, based on the dynamic response analysis of truss structures under stochastic process loads, the dynamic reliability constraints are developed and simplified, and the normalization of design variables is discussed to avoid some variables being drowned by others during optimization due to their different dimensions and orders of magnitude. The optimal models of dimension and shape with element or system dynamic reliability constraints are then presented. Two numerical examples are finally used to illustrate the results of different optimal designs, which demonstrate that the efficiency to solve the structural optimization with dynamic reliability constraints can be significantly improved if the design variables and their initial values are selected properly.     

Shape optimization method of free-form cable-braced grid shells based on the translational surfaces technique

Cable-braced grid shells, being a new type of single-layer reticulated shell, are widely used in glass roofs. However, research on the shape optimization of free-form cable-braced grid shells is relatively lacking. This paper describes a shape optimization method for cable-braced free-form grid shells, with strain energy used as the optimization object, structural height used as the optimization variable, and the conjugate gradient method used as the optimization algorithm. According to the shape forming method for grid shells, their shape optimization can be realized only by adjusting the generatrix and directrix, not by optimizing the whole surface. The B-spline curve method is used to model the generatrix and directrix and maintain an optimized surface fairing. The following conclusions can be drawn from this study. First, the structural mechanical behavior of grid shells can be significantly improved with rapid convergence using the proposed shape optimization method. Second, the plane quadrilateral mesh is maintained and fewer optimization variables are needed during the proposed shape optimization method. Finally, the optimized surface is fairing and the mechanical properties of the optimized surface are somewhat decreased when using the B-spline curve method.     

折板形网壳结构的设计及研究

以某体育馆钢屋盖结构为实例 ,论述了折板网壳结构的选型、受力特点、水平推力的处理方法和模态分析。研究发现 ,该结构的自振频率呈密集型分布 ,结构的基本振动为水平振动 ,而不象平板网架那样以竖向振动为主 ,结构表现出良好的受力性能和抗震性能     

钢筋混凝土空间网格结构

钢筋混凝土空间楼/屋盖网格结构包括平板型的空腹网架结构、空腹夹层板结构、空腹双重网格结构、现浇混凝土空心大板楼盖结构、钢筋混凝土空腹夹层板单向弯曲形成的钢筋混凝土空腹夹层网壳和网拱结构、双向弯曲成型的钢筋混凝土空腹夹层双曲扁网壳结构。这些新型结构体系自1980年起在公共建筑中应用达100多万平米。本文对这些结构的的特点和适应性进行了论述。